I just replied to your PM, but why not put it into this thread for everyone to see - in it's original grammar...:

so it all depends on which age range and which kind of people you are looking for. generally, like in most european cities from sun-wed, there are not too many options, but on weekends there is a ton happening. my favorite venues are volksgarten and platzhirsch, i have sarged there extensively.

volksgarten: open thu-sat, 25-30 crowd, really cool girls, and big too (for vienna standards); my favorite venue and the one i have had most success in.
platzhirsch: open thu-sat, about the same crowd, very international, bigger venue, but not too big.

i should also mention "passage", probably the most famous club in vienna, but in my opinion it sucks balls! really posh and the shields are miles high, music very loud too. i definitely don't recommend it for sarging, but hey, if you got good game and are looking for a challenge...

club couture: thu-sat, very big, not as posh, but not totally trashy either. younger girls (say, 18-24)
praterdom: this is, i believe, the biggest venue in vienna, trashy, i have never sarged there. young crowd, you will meet the hair dresser rather than the doctor here, so to speak...
palais palffy: fr-sat, rather posh, but not too much, not too big, somehow a "secret tip" almost. if you got game you could have fun here, two small floors, 25-35 and over crowd
pratersauna: big, a bit more on the alternative side, ok place
the box: fr-sat, over 30 crowd, rather on the posh side, but quite cool

if you are looking for bars: manolo's; or a lot of places around schwedenplatz (but girls are often below 20 there)

in regards to days of the week:

mon: never been out sarging, but probably "Q" or ride club (erasmus student party)
tue: definitely U4 (student party) or maybe passage (because of lack of alternative options)
wed:passage, lutz club (if open), look at list of link below;
thu: this is when the fun starts - volksgarten, platzhirsch, club couture
fr: any of the places mentioned above, there are lots of other venues too (see link below)
sat: same as friday
sun: dead as a rat's ass; if you can dance salsa, try floriditas; or try ride club (last time there were 25 people in there on a sun); stay home, rest!